Embodiments of the present invention relate generally to superjunction devices, and more particularly, to superjunction devices manufactured using wafer bonding.
Since the invention of superjunction devices by Dr. Xingbi Chen, as disclosed in U.S. Pat. No. 5,216,275, the contents of which are incorporated by reference herein, there have been many attempts to expand and improve on the superjunction effect of his invention. U.S. Pat. Nos. 6,410,958, 6,300,171, and 6,307,246 are examples of such efforts and are incorporated herein by reference.
Superjunction devices, including, but not limited to metal-oxide-semiconductor field-effect transistors (MOSFET), diodes, and insulated-gate bipolar transistors (IGBT), have been or will be employed in various applications such as automobile electrical systems, power supplies, and power management applications. For example, superjunction devices may specifically be employed in light emitting diode (LED) televisions, electric or hybrid cars, LED light bulbs, servers, tablets, uninterruptable power supplies (UPS), and the like. Such devices sustain high voltages in the off-state and yield low voltages and high saturation current densities in the on-state.
In conventional trench-type superjunction devices, the process typically involves deep trench etching, sidewall doping, and trench refill. Trench refill is performed using an insulative material, such as tetraethyl orthosilicate (TEOS), organic compounds, or the like. Trench refill further requires the steps of filling the trenches with the refill material, annealing, and planarizing. These additional process steps result in higher manufacturing costs, and introduce potential origins of defects, which impacts the production yield.
It is therefore desirable to provide a method of manufacturing superjunction devices with fewer process steps, that reduces thermal and mechanical stresses derived from particular process steps and materials, and lowers the overall production cost while raising the yield.